COCCOLITH PRODUCTION AND DETACHMENT BY EMILIANIA-HUXLEYI (PRYMNESIOPHYCEAE)

Laboratory experiments were performed with the prymnesiophyte Emiliani a huxleyi (Lohm.) Hay and Mohler, strain 88E, to quantify calcificatio n per cell, coccolith detachment, and effects of coccolith production on optical scattering of individual cells. C-14 incorporation into att ached and detached coccoliths was measured using a bulk filtration tec hnique. C-14-labeled cells also were sorted using flow cytometer and a nalyzed for carbon incorporation into attached coccoliths. The differe nce between the bulk and flow cytometer analyses provided a C-14-based estimate of the rate of production of detached coccoliths. Coccolith production and detachment were separated in time in batch cultures, wi th most detachment happening well after calcification had stopped. Acc umulation of coccoliths was maximum at the end of logarithmic growth w ith 50-80 coccoliths per cell (three to five complete layers of coccol iths around the cells). Net accretion rates of coccoliths were on the order of 7 coccoliths.cell-(1).d(-1) while net detachment rates were a s high as 15 coccoliths.cell(-1)d(-1) for stationary phase cells. Equa l numbers of coccoliths were attached and detached early in logarithmi c growth, and as cells aged, the numbers of detached coccoliths exceed ed the attached ones by a factor of 6. Our results demonstrate Pronoun ced changes of forward angle light scatter and 90 degrees light scatte r of cells as they grow logarithmically and enter stationary phase. Co unts of loose coccoliths in batch cultures are consistent with the det achment of coccoliths in layers rather than individual coccoliths.